Conventional process chambers utilizing an electrostatic chuck typically include a grid, or mesh electrode, embedded within the chuck that is biased negatively to create a static potential difference with the substrate, thereby chucking the substrate. The potential difference must be maintained at such a level as to prevent the substrate the moving during processing, or alternatively, prevent overchucking, which may lead to substrate breakage or improper cooling. To ascertain the proper potential difference, a self-bias of the substrate (e.g., a bias of the substrate due to capacitive coupling of the substrate during processing) must be calculated. However, the inventors have observed that conventionally used methodologies for calculating self-bias on a substrate in a process chamber may result in an inaccurate estimation of potential difference needed to properly chuck the substrate to a substrate support during processing. Moreover, conventional methodologies are typically only implemented for cases where a single bias power is used.
Therefore, the inventors have provided methods for calculating self-bias on a substrate in a process chamber utilizing substrate bias power having single or multiple frequencies.